Air-jet spinning machines with correspondingly equipped spinning units are known in the state of the art, and serve the purpose of the production of a yarn from an elongated fiber composite. In such machines, with the assistance of a vortex air flow produced by air jets within the spinning nozzle, the outer fibers of the fiber composite are wound in the area of an inlet mouth of the yarn formation element around the inner core fibers, and ultimately form the wrapped fibers crucial for the desired strength of the yarn. This creates a yarn with a twist, which ultimately can be led away from the spinning nozzle through a yarn guide channel and, for example, wound on a spool.
Spinning units conforming to this type are known in the state of the art, whereas the term “yarn” is generally understood to mean a fiber composite, for which at least one part of the fibers is wound around an inner core. As such, this includes, for example, a yarn in the conventional sense, which may be processed into a fabric, for instance with the assistance of a weaving machine. Likewise, the invention relates to spinning units of air-jet spinning machines, with the assistance of which so-called “roving” (another name: coarse roving) can be produced. Such roving is distinguished by the fact that, despite a certain strength, which is sufficient for carrying the yarn to a subsequent textile machine, it is still capable of being drafted. Thus, the roving can be drafted with the assistance of a drafting device, for example, the drafting system of a textile machine processing the roving, for example a ring spinning machine, before it is finally spun. For the purposes of this invention, the term “yarn” is understood to include yarn or roving produced with an air-jet spinning machine.
The production of man-made fibers, such as polyester, or mixtures of natural and man-made fibers, results in deposits on the surface of the yarn formation element. The production of man-made fibers includes a so-called “preparation” of the continuous fibers during the production process, wherein a preparation agent, mostly oils with various additives, is applied on the continuous fibers, which enables treatment of, for example, drafting of continuous fibers at high speeds. Such preparation agents sometimes adhere to the man-made fibers in further treatment, and lead to impurities in the air-jet spinning machine. Typically, the fibers fed to the air-jet spinning machine in the form of a fiber composite are fed to the spinning nozzle through a pair of delivery rollers. The pair of delivery rollers may correspond to a pair of output rollers of a drafting system. Drafting systems that are used serve the purpose of refining the advanced fiber composite prior to entering the spinning nozzle.
A fiber guide element is arranged in the entrance area of the spinning nozzle, through which the fiber composite is guided into the spinning nozzle to the yarn formation element. Multiple spindles with an inner yarn guide channel may be used as yarn formation elements. At the top of the yarn formation element, compressed air is introduced through the housing wall of the spinning nozzle in such a manner that a rotating vortex air flow arises. As a result, individual external fibers are separated from the fiber composite leaving the fiber guide element, and are turned over through the top of the yarn formation element. In the further course, these fibers that have broken away rotate on the surface of the yarn formation element. Subsequently, through the forward movement of the inner core fibers of the fiber composite, the rotating fibers are wound around the core fibers, and a yarn is thereby formed. Through the movement of the individual fibers on the surface of the yarn formation element, deposits form on the yarn formation element due to the buildups on the fibers from the production process. Deposits on the yarn formation element may also be caused by damaged fibers. For the same reasons, deposits may also arise on the surface of the interior of the spinning nozzle or the fiber guide element. These buildups lead to a deterioration of the surface condition of the yarn formation element, and cause a reduction in the quality of the yarn that is produced. A regular cleaning of the affected surfaces is necessary in order to be able to maintain a consistent quality of the spun yarns.
The cleaning of the surfaces of the yarn formation element, the interior of the spinning nozzle and the fiber guide element may take place manually through the periodic disassembly of the yarn formation element, but this leads to substantial maintenance, connected with a corresponding interruption in operations.
EP 2 450 478 discloses a device that allows for automatic cleaning to be carried out without stopping the machine. For this purpose, an additive is mixed with the compressed air used for the formation of vortex air flow within the spinning nozzle. The additive is guided by the compressed air to the yarn formation element, and results in the cleaning of the surface of the yarn formation element. It is disadvantageous to the disclosed cleaning system that, for the feeding of the additive, an additional compressed air supply of all of the spinning units of the air-jet spinning machine is necessary and, as a result of this, a complex governing of the dosing of the additive is to be provided in order to avoid an overdosing of the additive when individual spinning units have stopped. Moreover, the additive must be fed into a surrounding area with an increased ambient pressure, namely the air supply of the spinning nozzle, which makes corresponding demands on the dosing device for the adjustment to a momentarily prevailing ambient pressure.
JP-2008-095-208 discloses a further design of a cleaning of the yarn formation element. An additive is also fed to the compressed air used for agitation in the spinning nozzle, and is guided with this compressed air into the spinning nozzle and thus to the yarn formation element. In the disclosed design, the dosing and the addition of the additive is provided separately for each spinning unit. Also in this design, the additive must be fed into a surrounding area with an increased ambient pressure, which makes high demands on the dosing device.